Perennial wild plant mixtures for biomass production: Impact of species composition dynamics on yield performance over a five-year cultivation period in southwest Germany

The DMYs varied strongly between the mixtures, sites and years, ranging from 2.9-22.5 Mg ha−1 yr−1. Significant effects of mixture (P < 0.001) and site x age interactions (P < 0.05) were found. On average, S2 had about 55% higher yield than S1 over the five years (S2 accumulated DMY: 50.2-74.2 Mg ha−1 s). For both mixtures, a high number (up to 19) of WPM species were recorded, but this declined over the cultivation period at all sites. The DMYs at REN and SJO increased with time, whereas at HOH the high weed pressure from the grassland pre-crop resulted in decreasing yields. Here, the nitrogen mineralization of the grassland residues was high enough to mask fertilization effects. A good substrate quality for ensilaging (DMC >28%) was achieved at all sites every year except 2011. From these findings, we can recommend the WPM concept based on the S2 mixture as a feasible cultivation system with potentially high ecological benefits, in particular for marginal sites.